1. Field of the Invention
The present invention relates to an electrode assembly having steps, and more particularly, to an electrode assembly having steps in at least one corner portion thereof.
The present invention also relates to a secondary battery, a battery pack, and a device including the electrode assembly having steps.
2. Description of the Related Art
Recently, due to the technological development of mobile devices and increasing demand therefor, demand for rechargeable batteries (or secondary batteries) have rapidly increased. Accordingly, a secondary lithium battery having high energy density and a high operating voltage, as well as excellent charge and life span characteristics, has been widely used as an energy source of various electronic products as well as various mobile devices.
In general, a secondary lithium battery has a structure in which an electrode assembly and electrolyte are hermetically sealed within a battery case, and may be classified as a cylindrical battery, an angular battery, a prismatic battery, a pouch-type battery, or the like, according to appearance, and may be classified as a lithium ion battery, a lithium ion polymer battery, a lithium polymer battery, or the like, according to a type of electrolyte used therein.
Due to the recent trend for reductions in the size of mobile devices, demand for thin prismatic batteries and pouch-type batteries has been on the rise, and in particular, interest in lightweight pouch-type batteries has been increased.
In particular, mobile devices have been increasingly reduced in size and diversified in design. With a technology environment changing, a shape of a battery having conventional electrode units stacked therein does not correspond to a mobile device in terms of shape, resulting in a failure of effective utilization of internal space of the mobile device. Thus, batteries installed in mobile devices are required to have various shapes.
Hence, demand for batteries having steps has been increased. A shape of a battery having steps may maximally correspond to that of a device according to a shape thereof, minimizing dead space within the device, and thus, the device may be effectively filled with the secondary battery to increase overall battery capacity.
Meanwhile, recently, mobile devices having various designs incorporating rounded corners have been launched, and in order to be installed in such devices, demand for secondary batteries having rounded corners fitting the design of devices has increased.
In addition, the manufacture of multiple electrodes for an electrode assembly often occurs by producing multiple of the electrodes from a single sheet of material. Current processes for cutting or removing the electrodes from the material suffer from inefficiencies. One of those inefficiencies is the output of one or more electrodes that do not have the intended perimeter configuration for assembly into the battery cell. Specifically, the perimeter of the electrodes can include undesirable edge protrusions. These inefficiencies can slow and add cost to the process of manufacturing and assembling a battery cell according to the present invention.
Therefore, electrode units for providing a battery that may be able to be variously designed are required to be provided, and a method for promoting enhancement productivity by reducing a defect rate during an electrode unit fabrication process is required.
An aspect of the present invention provides an electrode assembly capable of providing secondary batteries having various designs without being restricted by a shape of a corner portion of an electrode unit.
An aspect of the present invention also provides a secondary battery, a battery pack, and a device including the foregoing electrode assembly.